1. Field
The present disclosure relates to a capacitive deionization apparatus and methods of treating a fluid using the same.
2. Description of the Related Art
In some regions, domestic water may include a relatively large amount of minerals. In Europe or other regions, limestone substances frequently flow in underground water, and thus tap water in these regions contains a relatively large amount of minerals. Water having a high mineral content (i.e., hard water) may cause problems in terms of the formation of lime scales in the interior walls of pipes and a sharp decrease in energy efficiency when it is used for home installations, for example, a heat exchanger or a boiler. In addition, hard water is inappropriate for use as wash water. Therefore, there has been some demand for technology for removing ions from hard water to make it into soft water, in particular, in an environmentally-friendly manner. Furthermore, demands for seawater desalination have increased as larger areas are suffering from water shortages.
A capacitive deionization (CDI) apparatus is a device for applying a voltage to porous electrodes having nano-sized pores to make them carry a polarity and thereby adsorb ionic materials from a medium such as hard water onto the surface of the electrodes and thus remove the same therefrom. In the CDI apparatus, when a medium containing dissolved ions flows between two electrodes of a positive electrode and a negative electrode and DC power having a low potential difference is applied thereto, the anionic components and the cationic components among the dissolved ions are adsorbed and concentrated onto the positive electrode and the negative electrode, respectively. When an electric current flows in a reverse direction between the two electrodes by, for example, short-circuiting the two electrodes, the concentrated ions are detached from the electrodes. Since the CDI apparatus does not require a high potential difference, its energy efficiency is high, harmful ions may be removed together with the hard components when the ions are adsorbed, and its recycling process does not need any chemicals.